Get RTC date

kernel/time/time.c

@@ -0,0 +1,96 @@
+#include <stdint.h>
+#include <stddef.h>
+#include "time.h"
+#include "hal/hal.h"
+
+#define CMOS_PORT     0x70
+#define CMOS_RETURN   0x71
+#define CMOS_STATA    0x0A
+#define CMOS_STATB    0x0B
+#define CMOS_UIP      (1<<7)
+
+#define SECS  0x00
+#define MINS  0x02
+#define HRS   0x04
+#define DAY   0x07
+#define MONTH 0x08
+#define YEAR  0x09
+
+void time_microdelay(void) {
+  for (volatile size_t i = 0; i < 200; i++);
+}
+
+uint32_t time_cmosread(uint32_t reg) {
+  io_out8(CMOS_PORT, reg);
+  time_microdelay();
+  return io_in8(CMOS_RETURN);
+}
+
+void time_fill(Time *time) {
+  time->second = time_cmosread(SECS);
+  time->minute = time_cmosread(MINS);
+  time->hour   = time_cmosread(HRS);
+  time->day    = time_cmosread(DAY);
+  time->month  = time_cmosread(MONTH);
+  time->year   = time_cmosread(YEAR);
+}
+
+void time_get(Time *time) {
+  Time t1, t2;
+  uint32_t sb, bcd;
+
+  sb = time_cmosread(CMOS_STATB);
+  bcd = (sb & (1<<2)) == 0;
+
+  for (;;) {
+    time_fill(&t1);
+    if (time_cmosread(CMOS_STATA) & CMOS_UIP) {
+      continue;
+    }
+    time_fill(&t2);
+    if (hal_memcmp(&t1, &t2, sizeof(t1)) == 0) {
+      break;
+    }
+  }
+
+  if (bcd) {
+    #define CONV(x)   (t1.x = ((t1.x >> 4) * 10) + (t1.x & 0xF))
+    CONV(second);
+    CONV(minute);
+    CONV(hour);
+    CONV(day);
+    CONV(month);
+    CONV(year);
+    #undef CONV
+  }
+
+  *time = t1;
+  time->year += 2000;
+}
+
+bool time_isleap(uint32_t y) {
+  return ((y % 4 == 0) && (y % 100 != 0) || (y % 400 == 0));
+}
+
+const uint16_t days_before_month[12] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
+
+timeunix_t time_tounix(Time *time) {
+  uint64_t days = 0;
+  for (uint32_t y = 1970; y < time->year; y++) {
+    days += time_isleap(y) ? 366 : 365;
+  }
+
+  days += days_before_month[time->month - 1];
+
+  if (time->month > 2 && time_isleap(time->year)) {
+    days += 1;
+  }
+
+  days += time->day - 1;
+
+  uint64_t secs = days * 86400;
+  secs += time->hour * 3600;
+  secs += time->minute * 60;
+  secs += time->second;
+  return secs;
+}